An Open Refrigerated Display Case and a Flow Stabilizing Device

ABSTRACT

An open refrigerated display case including: a refrigerated display area having one or more shelves; an air outlet and an air inlet opening into the display area and spaced from one another; a duct fluidically coupling the air inlet to the air outlet, the duct being configured to direct air flow out of the air outlet across the display area and toward the air inlet to form an air curtain across the display area; wherein each of the one or more shelves are provided with an associated flow stabilizing device; wherein the one or more flow stabilizing devices each include a cellular structure which extends transversely across the display area perpendicular to the direction of the air flow within the air curtain, the cellular structure forming a matrix of stabilizing channels; wherein the one or more flow stabilizing devices are each positioned so that the stabilizing channels receive the entire air curtain and stabilize the air flow within the air curtain; wherein an upper surface of the or each flow stabilizing device is arranged so as to be substantially level with or below an upper surface of the associated shelf.

BACKGROUND

The invention relates to an open refrigerated display case and a flow stabilizing device for an open refrigerated display case.

The display of chilled or frozen items is commonplace in many retail environments, most notably in supermarkets. Conventionally, such items have been displayed in refrigerated display cases having glass doors to allow customers to browse items before opening the doors to access the items. However, the presence of such doors has been seen as problematic in that they make it difficult for several customers to access the contents of the case, as well as providing an obstruction when open, narrowing the usable aisle space.

It is therefore common for supermarkets to use open-fronted display cases (Open Refrigerated Display Cases; herein “ORDCs”). ORDCs utilize an air curtain which is cooled to below ambient temperature and propelled downward, across the open front of the display case. The air curtain separates the refrigerated interior of the display case from the ambient air surrounding the display case. The air curtain thus keeps the cool air inside the display case from spilling out due to buoyancy effects, and also provides a barrier from other external motions of air around the display case. ORDCs therefore do not need any physical barrier separating customers from the contents of the display case. Accordingly, ORDCs provide a desirable method of displaying food and other perishable goods as they allow both easy access and clear visibility of merchandise.

However, as a direct consequence of their open design, ORDCs do have significantly higher energy consumption compared to the closed-fronted alternative. The main energy losses occur within the air curtain, and are caused by the entrainment of warm ambient air into the air curtain and the turbulent mixing which occurs within the air curtain itself. The entrainment of warm ambient air causes an increase in temperature within the air curtain, and this warmer air must be cooled as it re-circulates through the system. It has been estimated that 70% to 80% of the cooling load of an ORDC is due to such effects.

In recent years, multi-decked designs have become commonplace to maximize the display space per unit of floor space. Consequently, the air curtains of such ORDCs must seal a larger display area. This has exacerbated entrainment issues and the resulting energy losses, as well as making the design of air curtains more challenging, particularly in respect of ensuring product integrity and temperature homogeneity while attempting to minimize their energy consumption.

The invention thus seeks to improve the efficiency of ORDCs by reducing entrainment within the air curtain.

BRIEF SUMMARY

According to an aspect of the invention there is therefore provided an open refrigerated display case comprising: a refrigerated display area comprising one or more shelves; an air outlet and an air inlet opening into the display area and spaced from one another; a duct fluidically coupling the air inlet to the air outlet, the duct being configured to direct air flow out of the air outlet across the display area and toward the air inlet to form an air curtain across the display area; wherein each of the one or more shelves are provided with an associated flow stabilizing device; wherein the one or more flow stabilizing devices each comprise a cellular structure which extends transversely across the display area perpendicular to the direction of the air flow within the air curtain, the cellular structure forming a matrix of stabilizing channels; wherein the one or more flow stabilizing devices are each positioned so that the stabilizing channels receive the entire air curtain and stabilize the air flow within the air curtain; wherein an upper surface of the or each flow stabilizing device is arranged so as to be substantially level with or below an upper surface of the associated shelf.

The cellular structure is a honeycomb structure.

The flow stabilizing devices may be spaced from the air outlet and/or one another by a distance which corresponds to approximately 4 to 6 times a width of the air outlet.

The flow stabilizing devices may be spaced by a distance which corresponds to approximately 5 times a width of the air outlet.

Each flow stabilizing device may be connected to the one or more shelves.

Each flow stabilizing device may be pivotably connected to the one or more shelves.

Each flow stabilizing device may be configured so as to allow a position of the matrix of stabilizing channels relative to the shelf to be varied.

Each flow stabilizing device may be integrally forming in one of the shelves.

The stabilizing channels may each have a uniform cross-section along their length (i.e. they are parallel-sided).

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:

FIG. 1 is a side cross-sectional view of a conventional open refrigerated display case (ORDC);

FIG. 2 is a perspective view of a shelf having a flow stabilizing device according to an embodiment of the invention;

FIG. 3 is a side cross-sectional view of an ORDC according to an embodiment of the invention having a plurality of shelves with flow stabilizing devices as shown in FIG. 2;

FIG. 4 schematically shows air flow from the conventional ORDC of FIG. 1;

FIG. 5 schematically shows air flow from the ORDC of FIG. 3;

FIG. 6 is a plan view of a shelf having a flow stabilizing device according to another embodiment of the invention; and

FIG. 7 is a side cross-sectional view of an ORDC according to another embodiment of the invention having a plurality of shelves with flow stabilizing devices as shown in FIG. 6.

DETAILED DESCRIPTION

FIG. 1 shows a conventional ORDC 2. The ORDC 2 comprises a cabinet portion formed by a lower wall 4, a back wall 6, an upper wall 8, and left and right side walls (not shown). A lower panel 10, a back panel 12 and an upper panel 14 are disposed within the cabinet portion.

The lower, back and upper panels 10, 12, 14 form a display area 15 which is provided with a plurality of shelves 17 (six are shown) on which items may be displayed. The shelves 17 are affixed to the back panel 12.

As shown, the lower, back and upper panels 10, 12, 14 are spaced from the respective lower, back and upper walls 4, 6, 8 to form a duct 16. An intake grille 18 is provided at the lower panel 10 to form an inlet to the duct 16. Similarly, a discharge grille 20 is provided at the upper panel 14 to form an outlet from the duct 16. The intake grille 18 and the discharge grille 20 are thus fluidically coupled to one another by the duct 16. The intake grille 18 and the discharge grille 20 are spaced from the back panel 12 toward the front of the cabinet portion and ahead of the shelves 17.

A fan 22 and a heat exchanger 24 are located within the duct 16 adjacent to the intake grille 18 and thus are disposed between the lower wall 4 and the lower panel 10. The fan 22 draws air into the duct 16 via the intake grille 18 which then passes through the heat exchanger 24 where it is cooled to well below the ambient temperature.

After passing through the heat exchanger 24, the air continues through the duct 16 between the back wall 6 and the back panel 12. The back panel 12 is perforated allowing air to pass from the duct 16 into the display area 15 where it cools items located on the shelves 17 and on the lower panel 10.

The remaining air flows through the duct 16 to the discharge grille 20. The air is ejected from the discharge grille 20 and descends over the open front of the display area 15 to form an air curtain 26. The air curtain 26 passes from the discharge grille 20 to the intake grille 18, where it is drawn in by the fan 22 and re-circulated through the duct 16. The air curtain 26 thus forms a non-physical barrier which separates the display area 15 from the ambient air surrounding the ORDC 2.

As shown in FIG. 1, the air curtain 26 may be angled away from vertical by around 5-10°. This may be achieved by angling the discharge grille 20. In particular, the discharge grille 20 may be provided with a honeycomb panel (not shown) which rectifies the air flow as it exits the discharge grille 20 to provide laminar flow. The air curtain 26 may also deviate away from the back panel 12 as a result of the air passing through the perforations in the back panel 12. The intake grille 18 is therefore offset from the discharge grille 20 to allow for this.

FIG. 2 shows a flow stabilizing device 28 according to an embodiment of the invention which is fitted to one of the shelves 17 of the ORDC 2.

As shown in FIG. 2, each shelf 17 comprises a shelf portion 30 and a pair of brackets 32 which support the shelf portion 30 and are configured to be received within slots in the back panel 12 of the ORDC 2. A product information strip 34 extends across a front surface of the shelf portion 30 and has a channel for receiving tickets displaying information regarding the products on the shelf portion 30, such as the product's price.

The flow stabilizing device 28 comprises a pair of arms 36 a, 36 b. The arms 36 a, 36 b are affixed to either lateral side of the shelf 17 such that they are spaced from one another across the width of the shelf 17. Each of the arms 36 a, 36 b is connected at one end to the shelf 17 and extends away from the shelf 17 in a cantilevered manner to a free end. The arms 36 a, 36 b thus lie in the same plane as the shelf 17. The arms 36 a, 36 b may be connected to the shelf 17 in any suitable manner, such as via attachment to the shelf portion 30, the brackets 32 or the product information strip 34.

A pair of stabilizing beams 38 a, 38 b extend between the arms 36 a, 36 b. The stabilizing beams 38 a, 38 b are spaced from one another and run parallel to one another across the full width of the shelf 17 (and the display area 15). The stabilizing beams 38 a, 38 b are arranged so that their widths extend in a vertical direction, substantially perpendicular to the shelf 17. The stabilizing beams 38 a, 38 b are, however, angled relative to one another so that the gap between the stabilizing beams 38 a, 38 b tapers toward the lower end of the stabilizing beams 38 a, 38 b. The stabilizing beams 38 a, 38 b thus define a first slot 39 a having a vertical extent (length). The first slot 39 a comprises an inlet at an upper end and an outlet at a lower end. The inlet has a greater width than the outlet and a convergent throat is disposed between the inlet and the outlet. The stabilizing beams 38 a, 38 b may taper at an angle of greater than 0° and less than 20° to the vertical. The angle may, however, differ between the two stabilizing beams 38 a, 38 b within a single flow stabilizing device 28. In particular, as shown, the outermost stabilizing beam 38 a may be arranged vertically and the innermost stabilizing beam 38 b angled relative to the outermost stabilizing beam 38 a.

The outermost stabilizing beam 38 a may be provided with a product information strip which can be used to display information regarding the products on the shelf portion 30 if the product information strip 34 of the shelf 17 itself is obscured by the stabilizing beams 38 a, 38 b. Alternatively, the stabilizing beams 38 a, 38 b may be transparent to allow the product information strip 34 of the shelf 17 to be viewed. This may also prevent the stabilizing beams 38 a, 38 b from blocking light from a light source within the ORDC 2 and thus ensure proper illumination of the products within the ORDC.

As shown in FIG. 3, each of the shelves 17 is provided with a flow stabilizing device 28. The stabilizing beams 38 a, 38 b of each shelf 17 are spaced from the shelf 17 so as to form a second slot 39 b between the innermost stabilizing beam 38 b and the shelf 17. The stabilizing beams 38 a, 38 b are positioned such that the majority of the air curtain 26 passes between the stabilizing beams 38 a, 38 b, through the first slot 39 a. A portion of the air curtain 26 may pass between the innermost stabilizing beam 38 b and the shelf 17, through the second slot 39 b, or beyond the exterior surface of the outermost stabilizing beam 38 a. As described previously, the back panel 12 is perforated to allow air to pass from the duct 16 into the display area 15 where it cools items located on the shelves 17 and on the lower panel 10. The direction of air flow from the back panel 12 is thus predominantly perpendicular to that of the air curtain 26. The air from the back panel 12 is entrained with the portion of the air curtain 26 passing through the second slot 39 a which turns the air flow towards the direction of the air curtain 26. This reduces the effect the air flow from the back panel 12 has on the air curtain 26.

As described previously, the air curtain 26 may be angled away from vertical and the stabilizing beams 38 a, 38 b may be spaced progressively further from the shelf 17 (or, where the shelves are of different lengths, from the back panel 12) from the uppermost shelf 17 to the lowermost shelf 17 so as to be aligned with the air curtain 26. The spacing between the stabilizing beams 38 a, 38 b may increase from the uppermost flow stabilizing device 28 to the lowermost flow stabilizing device 28 to account for the air curtain 26 becoming thicker as it passes down the front of the ORDC 2.

As described previously, the intake grille 18 is not directly aligned with the discharge grille 20. To counteract this, the stabilizing beams 38 a, 38 b of the uppermost flow stabilizing device 28 are curved so that the air curtain 26 is turned slightly as it passes through this flow stabilizing device 28. As shown, the stabilizing beams 38 a, 38 b of the uppermost flow stabilizing device 28 may also run parallel to one another such that they do not converge.

FIGS. 4 and 5 provide a comparison of the flow characteristics of the air curtain 26 without the flow stabilizing devices 28 of the invention (FIG. 4) and with the flow stabilizing devices 28 (FIG. 5).

As shown in FIG. 4, the air leaves the discharge grille 20 as a coherent jet 40. However, without the flow stabilizing devices 28, the jet 40 soon becomes unstable in region 42, and begins to separate. This causes a high level of turbulent mixing in region 44 which warms the air curtain 26 considerably, thus warming the ORDC 2.

As shown in FIG. 5, with the flow stabilizing devices 28 attached to the shelves 17, the air again exits the discharge grille 20, but before the air curtain 26 can become unstable the flow stabilizing device 28 acts to re-stabilize the flow. As described previously, the stabilizing beams 38 a, 38 b converge such that, as a result of the Venturi effect, the air is accelerated as it passes through the first slot 39 a of the flow stabilizing device 28. The acceleration acts to further stabilize the air curtain 26. The width of the air curtain 26 is also reduced which helps maintain a thin shear layer throughout the length of the air curtain 26. The second slot 39 b formed between the innermost stabilizing beam 38 b and the shelf 17 further promotes stabilization of the air curtain 26 by drawing air from the back panel 12 into the air curtain 26.

The shelves 17 may be configured so as to allow the shelf portion 30 to be positioned at different angles. This may be beneficial for displaying different types of products. To allow for this, each flow stabilizing device 28 may be pivotably connected to the shelf 17 so that the flow stabilizing device 28 remains horizontal (or at some other predetermined orientation). For example, the arms 36 a, 36 b may be pivotably connected to the shelf 17. Alternatively, the arms 36 a, 36 b may each comprise first and second members connected to one another at an articulated joint. The arms 36 a, 36 b may also allow the distance of the stabilizing beams 38 a, 38 b from the shelf 17 to be varied. In particular, as the shelf 17 is angled away from horizontal, its horizontal extent will reduce so that the stabilizing beams 38 a, 38 b are located closer to the back panel 12. The arms 36 a, 36 b may therefore allow for this to be counteracted so that the stabilizing beams 38 a, 38 b remain in the correct position for the air curtain 26. For example, the arms 36 a, 36 b may allow the stabilizing beams 38 a, 38 b to be located in a plurality of positions (e.g. defined by discrete mounting holes or a continuous slot) or the arms 36 a, 36 b themselves may be connected to the shelf 17 in a plurality of positions. Alternatively, the arms 38 a, 38 b may comprise a telescoping arrangement to alter their length.

An initial study using Computational Fluid Dynamics has shown that the flow stabilizing device 28 of the invention could provide a reduction of around 40% in convective heat losses.

Although not shown, the flow stabilizing device 28 may comprise an injector port which receives additional air. For example, the injector port may be connected to the duct 16 via a conduit or the injector port may receive air which passes through the perforated back panel 12. The injector port may be located adjacent the inlet of the flow stabilizing device 28. The Venturi effect creates an area of low pressure within the flow stabilizing device 28 as the air curtain 26 is accelerated. This acts to draw in the additional air from the injector port which further increases the velocity of the air curtain, thus helping it to remain stable and intact in extreme ambient conditions.

The flow stabilizing devices 28 can be connected to a standard shelf 17 and thus allow the flow stabilizing devices 28 to be retrofit to existing ORDCs. The flow stabilizing devices 28 may, however, be integrally formed with the shelves 17 or the ORDC 2. In this respect, “integral” is intended to convey that the flow stabilizing devices 28 are located within the perimeter of the shelves 17, rather than being affixed thereto. Nevertheless, the flow stabilizing devices 28 may still be removable from the remainder of the shelf 17 to aid manufacturing and cleaning, for example.

Although each shelf 17 of the ORDC 2 has been described as having a flow stabilizing device 28, this need not be the case and only some of the shelves 17 may be provided with flow stabilizing devices 28. It is, however, desirable that the flow stabilizing devices 28 are provided at regular spacings of between 120 mm and 190 mm, which corresponds to approximately 4 to 6 times the width of the discharge grille 20, and preferably at spacings of around 160 mm (5 times the width of the discharge grille 20).

Although the flow stabilizing devices 28 have been described as being connected directly to the shelves 17, they may instead be connected to other parts of the ORDC 2. For example, the arms 36 a, 36 b of the flow stabilizing devices 28 may connect to the back panel 12 such that the flow stabilizing devices 28 are positioned between adjacent shelves 17 (or between the lowermost shelf 17 and the lower panel 10). In particular, the flow stabilizing devices 28 may be positioned just below each of the shelves 17. Alternatively, the flow stabilizing devices 28 may be connected to the left and right side walls of the ORDC 2. In this case, the arms 36 a, 36 b can be omitted and the stabilizing beams 38 a, 38 b connected directly to the ORDC 2.

The stabilizing beams 38 a, 38 b also need not lie in the plane of the shelf 17. For example, the stabilizing beams 38 a, 38 b may be offset from the shelf 17 such that they are not aligned with the product information strip 34, thus allowing the product information strip 34 to be viewed. This may be achieved by using arms which are stepped or otherwise configured so that the connection to the shelf 17 and the connection to the stabilizing beams 38 a, 38 b are offset from one another.

In certain embodiments, the stabilizing beams 38 a, 38 b may not converge and are instead arranged parallel to one another. Such parallel stabilizing beams 38 a, 38 b may guide the air flow and prevent expansion of the air curtain, thus still re-stabilizing the flow.

FIG. 6 shows a shelf 117 having a flow stabilizing device 128 according to another embodiment of the invention. As shown, the shelf 117 comprises a shelf portion 130 on which products may be displayed. The flow stabilizing device 128 is integrated into the shelf 117 to form a single component. The flow stabilizing device 128 forms a zone of the shelf 117 at or toward an outermost edge of the shelf 117 (i.e. furthest from the back panel 12 of the ORDC 2). The flow stabilizing device 128 comprises a honeycomb panel which is embedded within the shelf 117. The honeycomb panel forms a matrix of open hexagonal cells extending in the direction of the air curtain 26. Each cell forms a stabilizing channel through which air from the air curtain 26 (and optionally from the back panel 12) can pass. The honeycomb panel is positioned to receive the entire air curtain 26. The stabilizing channels have a uniform cross-section along their length such that the longitudinal axes of the sides extend parallel to one another. However, the stabilizing channels of adjacent flow stabilizing devices 128 may be angled relative to one another to redirect the air curtain.

As shown in FIG. 7, the flow stabilizing device 128 is substantially coplanar with the shelf 117. Specifically, an upper surface of the flow stabilizing device 128 (i.e. of the hexagonal cells) is substantially coplanar with an upper surface of the shelf portion 130. A lower surface of the flow stabilizing device 128 (i.e. of the hexagonal cells) may also be substantially coplanar with a lower surface of the shelf portion 130 such that the flow stabilizing device lies within the vertical bounds of the upper and lower surfaces of the shelf portion 130. The flow stabilizing device 128 thus forms an integral part of the shelf portion 130 which does not obstruct the view of and access to products located on the shelf portion 130, or on adjacent shelves 117.

As shown in FIG. 7, in use, the flow stabilizing device 128 acts to re-stabilize the flow of the air curtain 26 after it exits the discharge grille 20 before it can become unstable. Specifically, the stabilizing channels guide the air flow and prevent expansion of the air curtain 26 as it passes down the front of the ORDC 2. They may also redirect air from the back panel 12 toward the direction of the air curtain 26.

In other embodiments, the flow stabilizing device 128 may be a separate component which is attached to an existing shelf. This may allow the flow stabilizing device 128 to be angled relative to the shelf portion 130, particularly when the shelf 117 itself is inclined. In this manner, the flow stabilizing device 128 may also be offset from the shelf 117. However, even where the flow stabilizing device 128 is provided within the body of the shelf (as shown in FIG. 6), it may still be possible to angle the flow stabilizing device relative to the shelf portion 130. For example, the flow stabilizing device 128 may be pivotably mounted via a gimbal joint. With this arrangement, it may be desirable for the upper surface of the flow stabilizing device 128 to remain at or below the level of the upper surface of the shelf 117 at each angular position. It may also be possible to adjust the fore and aft position of the flow stabilizing device 128 within the body of the shelf. For example, the flow stabilizing device 128 may be mounted on rails to allow it to be moved. The flow stabilizing device 128 may be moved along the rails so as to receive the entire curtain. Cover plates may be provided to between the flow stabilizing device and the shelf 117 to maximize the usable area of the shelf portion 130.

Although the flow stabilizing device 128 has been described as being formed by a honeycomb panel, it will be appreciated that other cellular structures may be used with form a matrix of flow stabilizing channels.

Although the upper surface of the flow stabilizing device 128 has been described as being substantially coplanar with the upper surface of the shelf portion 130, it may also lie below the level of the upper surface of the shelf portion 130. It is, however, useful for the upper surfaces to be substantially coplanar so as to form a continuous surface. This may aid removing items from the shelf, particularly where they are heavy and the customer wishes to slide the item across the surface of the shelf. On the other hand, the lower surface of the flow stabilizing device 128 may terminate above or project below the lower surface of the shelf portion 130. However, it is desirable, particularly where the shelves are close together relative to the height of goods on the shelf portions 130, that the lower surface of the flow stabilizing device 128 terminates at or above the level of the shelf portion 130 so as not to obstruct the view of and access to the shelf 117 below.

The invention is not limited to the embodiments described herein, and may be modified or adapted without departing from the scope of the present invention.

To avoid unnecessary duplication of effort and repetition of text in the specification, certain features are described in relation to only one or several aspects or embodiments of the invention. However, it is to be understood that, where it is technically possible, features described in relation to any aspect or embodiment of the invention may also be used with any other aspect or embodiment of the invention. 

1-17. (canceled)
 18. An open refrigerated display case comprising: a refrigerated display area comprising one or more shelves; an air outlet and an air inlet opening into the display area and spaced from one another; a duct fluidically coupling the air inlet to the air outlet, the duct being configured to direct air flow out of the air outlet across the display area and toward the air inlet to form an air curtain across the display area; wherein each of the one or more shelves are provided with an associated flow stabilizing device; wherein the one or more flow stabilizing devices each comprise a cellular structure which extends transversely across the display area perpendicular to the direction of the air flow within the air curtain, the cellular structure forming a matrix of stabilizing channels; wherein the one or more flow stabilizing devices are each positioned so that the stabilizing channels receives the entire air curtain and stabilize the air flow within the air curtain; wherein an upper surface of the or each flow stabilizing device is arranged so as to be substantially level with or below an upper surface of the associated shelf; and wherein the cellular structure is a honeycomb structure.
 19. An open refrigerated display case as claimed in claim 18, wherein the flow stabilizing devices are spaced from the air outlet and/or one another by a distance which corresponds to approximately 4 to 6 times a width of the air outlet.
 20. An open refrigerated display case as claimed in claim 19, wherein the flow stabilizing devices are spaced by a distance which corresponds to approximately 5 times a width of the air outlet.
 21. An open refrigerated display case as claimed in claim 18, wherein each flow stabilizing device is connected to the one or more shelves.
 22. An open refrigerated display case as claimed in claim 21, wherein each flow stabilizing device is pivotably connected to the one or more shelves.
 23. An open refrigerated display case as claimed in claim 18, wherein each flow stabilizing device is configured so as to allow a position of the matrix of stabilizing channels relative to the shelf to be varied.
 24. An open refrigerated display case as claimed in claim 18, wherein each flow stabilizing device is integrally formed in one of the shelves.
 25. An open refrigerated display case as claimed in claim 18, wherein the stabilizing channels each have a uniform cross-section along their length. 